Tymshare was founded in 1964 by two engineers from General Electric, Tom O’Rourke and Dave Schmidt. They had planned on using a General Electric Company (GE) computer to provide computing services, mainly for scientific applications, but GE refused to sell them one because it would have competed with GE’s own service. In 1965 they acquired an SDS 940 and quickly expanded to provide access to many other systems.

Until the late 1970s, they acquired one company per year adding these assets to the firm while diversifying from scientific computing to business applications. In 1984, a recession and changing markets caused the firm to be sold to the McDonnell Douglas Corporation.